Controllable vehicle suspension system with a controllable magnetorheological fluid strut

ABSTRACT

The controllable suspension system includes a strut with a magnetorheological fluid damper. The magnetorheological fluid damper includes a longitudinal damper tubular housing having a longitudinally extending axis and an inner wall for containing magnetorheological fluid. The damper includes a piston head movable within the damper tubular housing along a longitudinal length the housing, with the damper piston head providing a first upper variable volume magnetorheological fluid chamber and a second lower variable volume magnetorheological fluid chamber, with a fluid flow gap between the upper and lower fluid chambers with a piston head fluid flow interface length HL, the damper piston having a longitudinal piston rod for supporting the piston head within the housing, with the piston supported within the housing with a piston rod bearing assembly disposed between the housing and the rod, with the piston rod bearing assembly having a piston rod bearing seal interface length BL, wherein contact between the piston head and the damper tubular housing inner wall is inhibited.

CROSS REFERENCE

This application claims the benefit of, and incorporates by reference,U.S. Provisional Patent Application No. 60/796,567 (CONTROLLABLE VEHICLESUSPENSION SYSTEM WITH A CONTROLLABLE MAGNETORHEOLOGICAL FLUID STRUT)filed May 1, 2006.

FIELD OF THE INVENTION

The invention relates to the field of suspension systems for controllingmotion. The invention relates to the field of controllable systems forcontrolling motion and providing support. More particularly theinvention relates to the field of controllable vehicle systems forcontrolling vehicle motions, and more particularly provides vehicle cabsuspensions with controllable magnetorheological fluid struts havingbeneficial motion control.

BACKGROUND OF THE INVENTION

There is a need for controllable struts for supporting a load whileproviding motion control and vibration isolation. There is a need forvehicle cab struts for isolating vibrations and controlling cab motions.There is a need for controllable magnetorheological fluid struts whichaccurately and economically control and minimize vibrations. There is aneed for an economically feasible method of making motion control strutsand vehicle suspension systems. There is a need for a robust suspensionsystem and struts for isolating troublesome vibrations and controllingvehicle motions. There is a need for an economic suspension systemproviding beneficial controlled motion and vibration isolation.

SUMMARY OF THE INVENTION

In an embodiment the invention includes a controllable suspension systemfor controlling the relative motion between a first body and a secondbody. The controllable suspension system including a strut with amagnetorheological fluid damper. The magnetorheological fluid damperincludes a longitudinal damper tubular housing having a longitudinallyextending axis, the longitudinal damper tubular housing having an innerwall for containing a magnetorheological fluid within the tubularhousing. The magnetorheological fluid damper includes a cantilevereddamper piston. The damper piston includes a piston head movable withinthe damper tubular housing along a longitudinal length of the tubularhousing. The damper piston head provides a first upper variable volumemagnetorheological fluid chamber and a second lower variable volumemagnetorheological fluid chamber, with the damper piston head having afluid flow gap between the first upper variable volumemagnetorheological fluid chamber and the second lower variable volumemagnetorheological fluid chamber with a piston head fluid flow interfacelength HL. The damper piston has a longitudinal piston rod forsupporting the piston head within the longitudinal damper tubularhousing. The piston is supported within the longitudinal damper tubularhousing with a piston rod bearing assembly disposed between thelongitudinal damper tubular housing and the longitudinal piston rod, thepiston rod bearing assembly having a piston rod bearing seal interfacelength BL, wherein contact between the piston head and the dampertubular housing inner wall is inhibited.

In an embodiment the invention includes a controllable damper forcontrolling motion. The controllable damper includes a longitudinaldamper tubular housing having a longitudinally extending axis and aninner wall for containing a magnetorheological fluid within the tubularhousing. The controllable damper includes a single ended damper piston.The damper piston includes a piston head movable within the dampertubular housing along a longitudinal length of the tubular housing withthe damper piston head providing a first upper variable volumemagnetorheological fluid chamber and a second lower variable volumemagnetorheological fluid chamber, with the damper piston head providinga fluid flow gap between the first upper variable volume fluid chamberand the second lower variable volume fluid chamber with a piston headfluid flow interface length HL. The damper piston has a longitudinalpiston rod for supporting the piston head within the longitudinal dampertubular housing. The damper piston is supported within the longitudinaldamper tubular housing with an upper piston rod bearing assemblydisposed between the longitudinal damper tubular housing and thelongitudinal piston rod, with the piston rod bearing assembly having apiston rod bearing seal interface length BL, wherein contact between thepiston head and the damper tubular housing inner wall is minimized andinhibited.

In an embodiment the invention includes a method of making acontrollable suspension system for controlling the relative motionbetween a first body and a second body. The method includes providing alongitudinal damper tubular housing having a longitudinally extendingaxis and an inner wall for containing a magnetorheological fluid withinthe tubular housing. The longitudinal damper tubular housing has a firstupper end and a second distal lower end. The method includes providing apiston rod bearing assembly. The piston rod bearing assembly has apiston rod bearing seal interface length BL for supporting a damperpiston within the longitudinal damper tubular housing. The methodincludes providing a damper piston, the damper piston including a pistonhead and a longitudinal piston rod for supporting the piston head withinthe longitudinal damper tubular housing. The method includes disposingthe piston rod bearing assembly in the longitudinal damper tubularhousing proximate the first upper end. The method includes receiving thedamper piston longitudinal piston rod in the piston rod bearingassembly, wherein the piston head is movable within the damper tubularhousing along the longitudinal length of the tubular housing. The damperpiston head provides a first upper variable volume magnetorheologicalfluid chamber and a second lower variable volume magnetorheologicalfluid chamber with the damper piston head having a fluid flow gapbetween the first upper variable volume magnetorheological fluid chamberand the second lower variable volume magnetorheological fluid chamberwith a piston head fluid flow interface length HL with contact betweenthe piston head OD and the damper tubular housing inner wall IDinhibited. The method includes providing a magnetorheological damperfluid and disposing the magnetorheological damper fluid in the dampertubular housing.

In an embodiment the invention includes a method of making acontrollable damper for controlling motion. The method includesproviding a longitudinal damper tubular housing having a longitudinallyextending axis and an inner wall for containing a fluid within thetubular housing. The longitudinal damper tubular housing has a first endand a second distal end. The method includes providing a piston rodbearing assembly, the piston rod bearing assembly having a piston rodbearing seal interface length BL for supporting a damper piston withinthe longitudinal damper tubular housing. The method includes providing adamper piston, the damper piston including a piston head and alongitudinal piston rod for supporting the piston head within thelongitudinal damper tubular housing. The method includes disposing thepiston rod bearing assembly in the longitudinal damper tubular housingproximate the first upper end. The method includes receiving the damperpiston longitudinal piston rod in the piston rod bearing assembly,wherein the piston head is movable within the damper tubular housingalong the longitudinal length of the tubular housing, with the damperpiston head providing a first upper variable volume fluid chamber and asecond lower variable volume fluid chamber and a fluid flow gap betweenthe first upper variable volume fluid chamber and the second lowervariable volume fluid chamber with a piston head fluid flow interfacelength HL, with HL<BL and contact between the piston head and the dampertubular housing inner wall inhibited.

In an embodiment the invention includes a method of making acontrollable damper for controlling motion. The method includesproviding a longitudinal damper tubular housing having a longitudinallyextending axis and an inner wall for containing a magnetorheologicalfluid within the tubular housing. The longitudinal damper tubularhousing has a first upper end and a second distal lower end. The methodincludes providing a piston rod bearing assembly, the piston rod bearingassembly having a piston rod bearing seal interface length BL forsupporting a damper piston within the longitudinal damper tubularhousing. The method includes providing a damper piston, the damperpiston including a magnetorheological fluid piston head and alongitudinal piston rod for supporting the piston head, themagnetorheological fluid piston head including an injected pressurizedpolymer overmolded electromagnetic magnetorheological fluid coil. Themethod includes disposing the piston rod bearing assembly in thelongitudinal damper tubular housing proximate the first upper end. Themethod includes receiving the damper piston longitudinal piston rod inthe piston rod bearing assembly wherein the magnetorheological fluidpiston head is movable within the damper tubular housing along thelongitudinal length of the tubular housing, with the damper piston headproviding a first upper variable volume magnetorheological fluid chamberand a second lower variable volume magnetorheological fluid chamber anda fluid flow gap between the first upper variable volumemagnetorheological fluid chamber and the second lower variable volumemagnetorheological fluid chamber. The method includes providing amagnetorheological damper fluid and disposing the magnetorheologicaldamper fluid in the damper tubular housing wherein a current supplied tothe overmolded electromagnetic coil controls the flow of themagnetorheological damper fluid proximate the injected pressurizedpolymer overmolded electromagnetic magnetorheological fluid coil.

In an embodiment the invention includes a method of making acontrollable damper for controlling motion. The method includesproviding a longitudinal damper tubular housing having a longitudinallyextending axis, the housing having an inner wall for containing amagnetorheological fluid within said tubular housing. The longitudinaldamper tubular housing includes a first upper end and a second distallower end.

The method includes providing a piston rod bearing assembly, the pistonrod bearing assembly having a piston rod bearing seal interface forsupporting a damper piston within said longitudinal damper tubularhousing. The method includes providing a damper piston, the damperpiston including a magnetorheological fluid piston head assembly and alongitudinal piston rod for supporting the piston head assembly, themagnetorheological fluid piston head assembly including a first uppermagnetic pole and a second lower magnetic pole with an overmoldedelectromagnetic magnetorheological fluid coil between the first uppermagnetic pole and the second lower magnetic pole. The first and secondmagnetic poles are formed from a magnetic material, and the overmoldedelectromagnetic magnetorheological fluid coil is formed from anelectrical conductor insulated wire coil overmolded with a nonmagneticpolymer with the nonmagnetic polymer including molded polymer coilguides. The method includes disposing the piston rod bearing assembly inthe longitudinal damper tubular housing proximate the first end, andreceiving said damper piston longitudinal piston rod in the piston rodbearing assembly. The magnetorheological fluid piston head is movablewithin the damper tubular housing along the longitudinal length of thetubular housing, with the damper piston head providing a first uppervariable volume magnetorheological fluid chamber and a second lowervariable volume magnetorheological fluid chamber. The damper piston headprovides a fluid flow gap between the first upper variable volumemagnetorheological fluid chamber and the second lower variable volumemagnetorheological fluid chamber. The method includes providing amagnetorheological damper fluid and disposing the magnetorheologicaldamper fluid in the damper tubular housing wherein a current supplied tothe overmolded electromagnetic magnetorheological fluid coil controlsthe flow of the magnetorheological damper fluid proximate the overmoldedelectromagnetic magnetorheological fluid coil.

In an embodiment the invention includes a controllable damper forcontrolling motion. The controllable damper includes a longitudinaldamper tubular housing having a longitudinally extending axis, thelongitudinal damper tubular housing having an inner wall for containinga fluid within said tubular housing, the damper tubular housing innerwall having a damper tubular housing inner wall ID. The controllabledamper includes a damper piston, the damper piston comprised of a pistonhead movable within the damper tubular housing along a longitudinallength of said tubular housing, the piston head having a piston head OD,with the damper piston head providing a first upper variable volumefluid chamber and a second lower variable volume fluid chamber. Thedamper piston head having a fluid flow gap between said piston head ODand damper tubular housing inner wall ID, and between the first uppervariable volume fluid chamber and the second lower variable volume fluidchamber with a piston head fluid flow interface length HL. The damperpiston having a longitudinal piston rod for supporting the piston headwith a piston rod bearing assembly disposed between the longitudinaldamper tubular housing and the longitudinal piston rod. The damperincludes a means for inhibiting contact between the piston head OD andthe damper tubular housing inner wall ID.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary of the invention, andare intended to provide an overview or framework for understanding thenature and character of the invention as it is claimed. The accompanyingdrawings are included to provide a further understanding of theinvention, and are incorporated in and constitute a part of thisspecification. The drawings illustrate various embodiments of theinvention, and together with the description serve to explain theprincipals and operation of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings.

In an embodiment the invention includes a controllable suspension systemfor controlling the relative motion between a first body and a secondbody. The controllable suspension system 20 controls the relative motionbetween a first body 22 and a second body 24 such as shown in FIG. 1-3.In preferred embodiments the controllable suspension system 20 is avehicle controllable suspension system 20, most preferably as shown inFIG. 1-3 a cab suspension controllable suspension system 20, with thesuspension system controlling motion between the vehicle cab body 22 andthe vehicle frame body 24. In alternative embodiments the suspensionsystem is a non-vehicle suspension system, preferably a stationarysuspension system. The controllable suspension system 20 includes atleast one strut 30. The controllable suspension system strut 30 includesa single ended magnetorheological fluid damper 32, preferably acantilevered single ended magnetorheological fluid damper. Themagnetorheological fluid damper 32 includes a longitudinal dampertubular housing 34 having a longitudinally extending axis 36, thelongitudinal damper tubular housing 34 having an inner wall 38 forcontaining a magnetorheological fluid 40 within the tubular housing 34.Preferably the longitudinal damper tubular housing 34 is comprised of amagnetic metal material, preferably a magnetic low carbon steel ascompared with a nonmagnetic metal material such as stainless steel.Preferably the magnetorheological fluid 40 is a magnetorheologicaldamper fluid with the fluid containing iron particles wherein therheology of the damper fluid changes from a free flowing liquid to aflow resistant semi-solid with controllable yield strength when exposedto a magnetic field, such as the LORD MR fluids available from LORDCorporation, Cary, N.C. The magnetorheological fluid damper 32 includesa cantilevered damper piston 42, the damper piston 42 including a pistonhead 44 movable within the damper tubular housing 34 along alongitudinal length of the tubular housing axis 36. The damper pistonhead 44 provides a first upper variable volume magnetorheological fluidchamber 46 and a second lower variable volume magnetorheological fluidchamber 48. The damper piston head 44 has a fluid flow gap 50 betweenthe first upper variable volume magnetorheological fluid chamber 46 andthe second lower variable volume magnetorheological fluid chamber 48with a piston head fluid flow interface length HL, with the fluid flowgap 50 between the piston head 44 and inner wall surface 38 of thetubular housing 34 with a piston gap Pgap between the OD of the pistonhead 44 and the ID of the inner wall 38. The damper piston 42 includes alongitudinal cantilevered piston rod 52 for supporting the piston head44 within the longitudinal damper tubular housing 34. The damper piston42 is supported within the longitudinal damper tubular housing 34 withan upper piston rod bearing assembly 54 disposed between thelongitudinal damper tubular housing 34 and the longitudinal piston rod52. The piston rod bearing assembly 54 has a piston rod bearing sealinterface length BL with BL>HL and contact between the piston head 44and the damper tubular housing inner wall 38 is inhibited. Preferablythe bearing assembly 54 has a minimal bearing gap Bgap between thebearings 56 and the OD of the piston rod 52. As shown in FIG. 6G,preferably [Pgap/(HL+Stroke)] is greater than (Bgap/BL). Preferably thepiston head 44 is a wear-band-free piston head, with the fluid flow gap50 maintained between piston head sides OD and tubular housing innerwall ID with no wear band or seal on the piston between piston head 44OD and inner wall 38 ID. In embodiments such as shown in FIG. 6L-6N,axially aligned coil guides 95 are preferably utilized to maintain fluidflow gap 50 and inhibit contact between the piston head 44 and thehousing wall 38. Preferably the axially aligned coil guides 95 arealigned with axis 36, and preferably substantially equally spaced aroundthe outside perimeter of EM coil 94, preferably with at least three coilguides 95, more preferably at least four guides, more preferably atleast five guides, and more preferably at least six guides spaced aroundthe OD of EM coil 94, preferably with the guides 95 occupying less than15% of the perimeter of the EM coil, and more preferably no greater than10% of the perimeter of the EM coil. Preferably the guides 95 are anonmagnetic material, preferably a polymer, preferably with the guides95 comprised of injection pressurized polymer 110 with the guides moldedintegral and simultaneously with their adjacent bobbin polymer overmold110 that is pressure injected into a overmold 106, with the nonmagneticpolymer guides and overmold polymer 110 encompassing and covering theunderlying wound EM coil wiring 102. Preferably the axially alignedguides 95 axially extend over the adjacent magnetic poles 96. Thecantilevered damper piston 42 preferably minimizes the off stateresistance of the damper with a minimized parasitic drag and resistance.Preferably the cantilevered damper piston 42 off state energydissipation is minimized by substantially inhibiting contact betweenpiston head 44 and housing wall 38 while maintaining the predeterminedfluid flow gap 50 and the gap width Pgap, preferably while not utilizinga piston wear band or piston seal that encircles the piston perimeter.

Preferably the piston 42 has a constant bearing length in that thepiston head 44 has no substantial bearing contact with the housing innerwall 38, with the cantilevered piston 42 providing a single ended damper32 as compared to a double ended damper. Preferably the rod 52terminates with the piston head 44, with the piston head unconnected tothe housing 34 except for the single bearing assembly 54. Preferably therod 52 and the piston head 44 are unconnected to the lower housing end58 distal from the piston rod bearing 54 and the upper housing end 60.Preferably the only mechanical connection of the piston head 44 is withthe single piston rod 52 extending to the upper bearing assembly 54,with rod 52 terminating with the piston head 44, with no contact ofpiston head 44 with housing inner side walls 38 or the lower damper end58 distal from the upper damper end 60 with the bearing 54. Inembodiments contact of piston head 44 is inhibited with minimizedperimeter occupying axially aligned guides 95. Preferably the pistonhead 44 is free of internal fluid flow conduits, preferably withsubstantially all fluid flow between the piston head 44 and housing 34through the fluid flow gap 50, preferably with the fluid flow gapmaintained with assistance of guides 95 which assist in ensuring thatsubstantial contact between the piston head 44, particularly themagnetic poles 96, and the housing inner side walls 38 is inhibited.Preferably the magnetorheological fluid damper 32 includes an uppervolume compensator 62. The magnetorheological fluid damper volumecompensator 62 preferably is proximate the piston rod bearing assembly54. Preferably the volume compensator 62 is adjacent the upper pistonrod bearing 54. Preferably the bearing holder support structure housing55 and the volume compensator housing are integrated together to providean upper bearing gas charged compliance member. Preferably the gascompliance volume compensator 62 is in fluid communication with thefirst upper variable volume magnetorheological fluid chamber 46, withthe volume compensator proximate the upper bearings 56 and the pistonrod 52, preferably with upper fluid chamber 46 and volume compensator 62in use in the suspension system 20 oriented on top relative to the forceof gravity to allow gas bubble migration into volume compensator 62.Preferably the damper 32 configuration provides for a dry assemblyprocess with the magnetorheological fluid filled into the damper afterthe piston 42 is assembled into the housing 34, and preferably then gaspressure charging of gas compliance volume compensator 62.

Preferably the strut 30 includes a longitudinal air gas spring 64, withthe longitudinal gas spring 64 aligned with the longitudinal dampertubular housing longitudinally extending axis 36. Preferably the strut30 includes the strut air spring 64 and the magnetorheological fluiddamper 32 aligned with the common center axis 36 and packaged togetherwith the gas spring 64 encompassing the damper 32, with the upper end ofthe damper including the piston rod 52, substantially housed within thegas spring 64. Preferably the upper end of the strut 30 includes anupper strut end head member 66 for attachment to the uppermost firstbody 22. Preferably the upper strut end head member 66 includes anelectrical power input 68 and an air compressed gas input 70. Preferablythe upper strut end head member 66 has an internal head cavity housingthat includes a strut control system 72 with an electronic controlcircuit board 74, gas spring air sleeve leveling valve 76, andpreferably also includes a high speed electrical communicationsconnection 78, such as a CAN-Bus, for receiving outside the strutsignals in addition to electrical power input 68. Preferably the upperstrut end head member 66 includes a strut sensor system 80, preferablythe upper sensor head end of the magneto-strictive longitudinal sensor80 that is aligned with the piston rod 52 and axis 36 and housed withinthe piston rod the 52. Preferably the piston rod 52 is comprised of anonmagnetic material, preferably a nonmagnetic metal such as stainlesssteel, wherein the inner housed magneto-strictive longitudinal sensor 80provides for sensing the stroke position of the piston along the strokelength of the damper. Preferably the upper strut end member housing 66includes the strut control system with sensors inputs, sensors, currentsupply, and also the pneumatic leveling valve to control leveling of thegas spring 64 in addition to controlling the magnetorheological fluiddamper 32.

Preferably the upper piston rod bearing assembly 54 includes a bearingholder support structure 55 which receives a first upper bearing 56 anda distal second lower bearing 56 to provide the piston rod bearing sealinterface length BL. Preferably the bearing holder support structure 55receives a bearing seal 53 between the lower bearing 56 and the upperfluid chamber 46. Preferably the upper piston rod bearing assembly 54includes the bearing holder support structure 55 which receives the atleast first bearing 56 and includes compliance member cavity 82 forreceiving a volume compensator gas compliance member 84, preferably withthe gas compliance member flexible fluid gas partition diaphragm 84flexibly fixed to the support structure 55 allowing expansion andcontraction of the gas filled diaphragm cavity to compensate formagnetorheological fluid volume changes, preferably with the gascompliance member flexible elastomer fluid gas partition diaphragm 84radially expandable between the support structure 55 and the housing 34.Preferably the upper piston rod bearing assembly 54 includes the bearingholder support structure 55 which receives the at least first bearing 56and includes a sensor target magnet holder 86 which receives a targetmagnet 88 for the magnetostrictive sensor 80 in the non-magnetic pistonrod 52. Preferably the upper volume compensator 62 is verticallyoriented relative to gravity in operation of the suspension system withthe volume compensator proximate the piston rod bearing.

Preferably volume compensator 62 is adjacent the upper piston rodbearing assembly 54, preferably with the bearing holder supportstructure 55 and volume compensator housing cavity 82 integrated toprovide an upper damper rod bearing gas charged compliance member.Preferably the rod bearing gas charged compliance member supportstructure 55 includes a gas compliance charging conduit 90 for fillingthe cavity 82 with a pressurized gas, preferably after the piston hasbeen assembled into the housing and bearing and the damper has beenfilled with the magnetorheological fluid. Preferably the volumecompensator 62 is in fluid communication with the adjacent damper fluidchamber 46 through a plurality of fluid volume compensating conduits 92between the housing 34 and the piston rod 52, which allow flow of fluidinto and out of the volume compensator, preferably with the conduits 92providing for greater flow than the piston head gap 50, preferably arelatively high flow into and out compared to piston head flow, withrelatively low resistance to flow into the volume compensator such thatit is not dynamically isolated from the rest of the workingmagnetorheological fluid.

The piston head 44 includes the electromagnetic coil 94 and an upper andlower magnetic pole 96 for controlling the flow of magnetorheologicalfluid 40 between the upper and lower chambers 46 and 48, preferably withthe electromagnetic coil 94 comprised of an electrically insulatedencapsulant injected pressurized polymer overmolded electromagneticmagnetorheological fluid coil 94. The preferred modular componentinjected pressurized polymer overmolded electromagneticmagnetorheological fluid coil 94 is shown in FIG.7. Preferably the EMcoil insulated wire 102 is wound on a non-magnetic plastic bobbin 104,with the coiled wire 102 on the bobbin 104 pressure overmolded with aninjected pressurized non-magnetic polymer 110 in a pressurized injectionovermold 106 under an applied pressure 107. Preferably the pressurizedinjection overmolded EM coil 94 includes a first and second wire pins108 for connection with a current supply wire circuit 100. Preferablythe modular component pressurized injection overmolded EM coil 94 issandwiched between upper and lower magnetic metal poles 96, to providethe current controllable EM coil piston head 44, with the modularcomponent pressurized injection overmolded EM coil 94 overmolded EM coiland poles 96 sized to provide the predetermined gap 50 with the housinginner wall 38, with the pressurized injection overmolded EM coilmagnetic field controlling magnetorheological fluid flow proximate thepiston head EM coil, with preferred embodiments molded with axiallyaligned guides 95 as shown in FIG. 7L-N. FIG. 6N show two overmolded EMcoils with molded guides 95 placed head to head to illustrate how theguides 95 extend beyond the coil top and bottom sides such that theywill overlap the adjacent magnetic poles when assembled into the pistonhead, with the guides equally spaced around the EM coil outer perimeterin a piston axially centering pattern centered and aligned with thelongitudinal extending axis 36 of damper 32.

Preferably the controllable suspension system 20 includes a first strut30 and at least a second cantilevered magnetorheological fluid damperstrut 30 between the first body 22 and the second body 24, preferablywith both struts 30 having outer encompassing air spring sleeves 64.Preferably the controllable suspension system 20 includes a thirdcantilevered magnetorheological fluid damper strut 30 between the firstbody and the second body. Preferably at least two of the more than onestruts 30 operate independently with their own self contained sensor andcontrol systems in their strut head member housing 66, preferably withno master control signals communicating between the at least two strutsfrom a suspension system master controller. Preferably the struts 30 areself-contained self-controlled struts that house their own controlsystems, preferably with only electrical power and compressed gassupplied from a master suspension system source, such as a vehiclebattery electrical power system and a compressed air system. In apreferred embodiment with the more than one strut 30 operating,preferably such as with four struts, a first master controlling strut30″ controls a second controlled dependent strut 30′ with master controlsignals communicating between the at least two struts 30″ and 30′, suchas with the master strut 30″ that sends controls to the other dependentstrut 30″ in addition to its own control. In a preferred embodiment thesuspension system 20 is a cab suspension system with two back cab struts30 and the front of the vehicle cab is mounted without such controllablecantilevered magnetorheological fluid damper struts 30, such as hardmount or mounted with noncontrolled elastomer mounts. In a preferred cabsuspension system 20 embodiment with two rear back cab struts 30 and thefront of the vehicle cab is mounted without such controllablecantilevered magnetorheological fluid damper struts 30, the struts 30are self controlled and autonomous with each having its own circuitboard control system, with the strut control system sharing andcommunicating its sensor data, such as its processed accelerometerinformation, with each other through the electrical communicationconnection 78 link to control roll of the cab body. In preferredembodiments the controllable magnetorheological fluid damper struts 30are self controlled and autonomous with each having its own circuitboard control system 72 housed in its upper strut end head member 66,with the struts control system sharing its sensor data through itselectrical communication connection 78 to control a motion of the cabrelative to the frame, such as to control roll, or with a four pointstrut suspension controlling roll and pitch of the cab with the fourself controlled sensor data sharing struts 30. In a preferred embodimentat least three struts 30 provide for a three point cab suspension systemfor control of roll and pitch, preferably with three independentself-controlled struts 30, 30, and 30′ and one dependent strut 30″.

In an embodiment the invention includes a controllable damper forcontrolling motion. The controllable damper 32 provides for thecontrolling or relative motion between a first body 22 and a second body24, preferably with the damper controlling motion in a vehicle, mostpreferably in a suspension system 20 between a vehicle frame and thevehicles cab. In alternative embodiments the damper 32 provides forcontrolling motion in non-vehicle stationary suspensions. Thecontrollable damper 32 includes a longitudinal damper tubular housing 34having a longitudinally extending axis 36. The longitudinal dampertubular housing 34 has an inner wall 38 for containing amagnetorheological fluid 40 within the tubular housing, with the damperhousing having an upper damper end 60 and a lower damper end 58. Thecontrollable damper 32 includes a cantilevered single ended damperpiston 42. The damper piston 42 includes a piston head 44 movable withinthe damper tubular housing 34 along a longitudinal stroke length of thetubular housing, with the damper piston head 44 providing a first uppervariable volume magnetorheological fluid chamber 46 and a second lowervariable volume magnetorheological fluid chamber 48. The damper pistonhead 44 has a fluid flow gap 50 between the first upper variable volumemagnetorheological fluid chamber 46 and the second lower variable volumemagnetorheological fluid chamber 48 with a piston head fluid flowinterface length HL, preferably with the gap 50 having a width Pgapbetween the piston head OD and inner surface ID of the tubular housing34. The damper piston 42 has a longitudinal piston rod 52 for supportingthe piston head 44 within the longitudinal damper tubular housing 34.Preferably the cantilevered piston rod 52 is the only mechanical supportfor supporting the piston head within the damper housing with a bearing.The piston 42 is supported within the longitudinal damper tubularhousing with an upper piston rod bearing assembly 54 disposed betweenthe longitudinal damper tubular housing 34 and the longitudinal pistonrod 52. The piston rod bearing assembly 54 having a piston rod bearingseal interface length BL, wherein contact between the piston head 44 andthe damper tubular housing inner wall 38 is inhibited. Preferably thepiston head 44 is a wearbandfree piston head, with themagnetorheological fluid flow gap width Pgap maintained between pistonhead OD sides and tubular housing inner wall with no wear band or sealon the piston head or between the piston OD sides and the inner wall.Preferably the damper 32 minimizes off state resistance a minimizedparasitic drag and resistance. Preferably the off state energydissipation of damper 32 when no controlling current is supplied to thepiston head EM coil 94 is minimized by inhibiting contact between thepiston head and housing wall while maintaining the predeterminedmagnetorheological fluid flow gap cylindrical shell of length HL andthickness Pgap. Preferably the piston 42 has a constant bearing lengthBL in that the piston head 44 has no bearing contact with the housinginner wall 38. Preferably the damper 32 is a single ended damper ascompared to a double ended damper, preferably with the rod 52terminating with the piston head 44, with the piston head otherwiseunconnected to the housing and the lower housing end 58 distal from thepiston rod bearing 54, preferably with the only mechanical connection ofthe piston head 44 with the single piston rod extending to the upperbearing assembly, with the rod terminating in the piston head.Preferably the piston head 44 is free of internal fluid flow conduitsinside the piston head OD, preferably with substantially all fluid flowof the magnetorheological fluid 40 between the piston head and thehousing through the magnetorheological fluid flow gap 50. Preferably thecontrollable damper 32 cantilevered piston length BL is greater than thepiston head cylindrical shell gap length HL.

Preferably the controllable magnetorheological fluid damper 32 includesan upper damper volume compensator 62. The volume compensator 62 isproximate the piston rod bearing assembly 54. Preferably the gascompliance volume compensator 62 is adjacent the upper piston rodbearing 54, preferably with the bearing holder support structure 55 andthe volume compensator housing cavity 82 integrated into an upperbearing gas charged compliance member. Preferably the gas compliancevolume compensator 62 is in fluid communication with the first uppervariable volume magnetorheological fluid chamber 46, with the volumecompensator proximate the upper bearing and the piston rod, preferablywith upper fluid chamber 46 and volume compensator 62 in use oriented ontop of lower fluid chamber 48 relative to the force of gravity to allowgas bubble migration upward into volume compensator 62. Preferably thedamper 32 provides for a dry assembly process with magnetorheologicalfluid filled after the piston 42 is assembled in the housing34,preferably through a lower housing end opening 59, then gas pressurecharging of the gas compliance volume compensator 62 through an upperend conduit 90. Preferably the piston rod bearing assembly bearingholder support structure 55 includes fluid flow conduits 92 to allowflow of fluid into and out of the volume compensator, preferably withconduits 92 providing for greater flow than the magnetorheologicalpiston head gap 50, preferably with relatively high flow into and out ofthe volume compensator as compared to piston head flow, with relativelylow resistance to flow into volume compensator.

Preferably the controllable magnetorheological fluid damper 32 includesan upper strut end head member 66 with an electrical power input 68.Preferably the upper strut end head member houses the damper controlsystem 72 with electronic control circuit board 74. In a preferredembodiment the power input is included with a multiple wire arrayconnector 78, such as a CAN bus electrical connector 78, preferably withthe multiple wire electrical connection providing for receiving outsidethe strut damper control signals in addition to electrical power inputthat generates the magnetorheological fluid controllable magnetic field.Preferably the upper strut end head member houses the damper controlsensor system, preferably including the upper head end of themagneto-strictive longitudinal sensor 80 that is aligned axis 36 andhoused within the piston rod 52. Preferably the upper strut end headmember housing includes the control system for also controlling levelingwith the gas spring with a leveling valve 76 for controlling pneumaticleveling of the strut 30. Preferably the strut and damper with the upperstrut end head member 66 is an intelligent self-contained damper systemwith the head member containing the electronics control system circuitboards 74 that receives sensor inputs such as from the magnetostrictivesensor 80 and accelerometers 120, and controls the electrical currentsupplied to the piston head EM coil 94 through the current supply wirecircuit 100 to control the damper 32, preferably with the controlelectronics including accelerometer sensors 120, preferably an at leastone accelerometer axis acceleration sensed, preferably with a firstaccelerometer axis 122 aligned with the damper axis 36. Preferably theaccelerometer sensor 120 is an at least two axis accelerometer, and mostpreferably a three axis accelerometer, with the first axis 122 alignedwith the damper axis 36, the second and third axis normal to the damperaxis 36.

Preferably the controllable magnetorheological fluid damper upper pistonrod bearing assembly 54 includes a bearing holder support structure 55which receives a first upper bearing 56, a distal second lower bearing56, and a piston rod seal 53 to provide the piston rod bearing sealinterface length BL. Preferably the controllable magnetorheologicalfluid damper upper piston rod bearing assembly 54 includes bearingholder 55 which receives at least first bearing 56 and a compliancemember cavity 82 for receiving a volume compensator gas compliancemember 84. Preferably the controllable magnetorheological fluid damperupper piston rod bearing assembly 54 includes bearing holder 55 whichreceives at least first bearing 56 and a sensor target magnet holder 86which receives a target magnet 88 for producing a sensor signal in theproximate magnetostrictive sensor 80 in the non-magnetic piston rod 52,to provide a sensed measurement of the location of the target magnetalong the length of sensor 80 to provide a measurement of the strokeposition of the piston head in the damper housing that is used as aninput into the damper electronic control system.

Preferably the controllable magnetorheological fluid damper piston head42 includes an insulating encapsulant injected pressurized polymerovermolded electromagnetic coil 94, with the piston head, overmoldedelectromagnetic coil and magnetic poles ODs sized to provide thepredetermined gap Pgap with the housing inner wall ID, with the gap 50maintained to inhibit contact with the wall 38 and to provide the fluidflow gap 50 with the coil 94 producing a magnetic field for controllingmagnetorheological fluid flow through the gap. The controllable pistonhead electromagnetic coil 94, upper and lower magnetic poles 96 with avariable applied current producing a controlling magnetic field forcontrolling the flow of magnetorheological fluid 40 between the upperand lower chambers 46 and 48, with the electromagnetic coil 94 comprisedof an electrically insulated injected pressurized polymer overmoldedelectromagnetic magnetorheological fluid coil 94. The preferred modularcomponent injected pressurized polymer overmolded electromagneticmagnetorheological fluid coil 94 is shown in FIG.7A-I. Preferably the EMcoil insulated wire 102 is wound on the non-magnetic plastic bobbin 104,with the coiled wire 102 on the bobbin 104 pressure overmolded with theinjected pressurized polymer 110 in the pressurized injection overmold106 under an applied pressure 107. Preferably the pressurized injectionovermolded EM coil 94 includes first and second wire pins 108 forconnection with a current supply wire circuit 100 that supplies thecontrolling current output by the control system. Preferably the modularcomponent pressurized injection overmolded EM coil 94 is sandwichedbetween the upper and lower magnetic metal poles 96, to provide thecurrent controllable EM coil piston head 44, with the modular componentpressurized injection overmolded EM coil 94 overmolded EM coil and poles96 sized to provide the predetermined gap 50 with the housing inner wall38, with the pressurized injection overmolded EM coil magnetic fieldcontrolling magnetorheological fluid flow proximate the piston head EMcoil.

In an embodiment the invention includes a method of making acontrollable suspension system for controlling the relative motionbetween a first body and a second body. Preferably the inventionprovides a method of making a controllable vehicle suspension system forcontrolling the relative motion between a first vehicle body and asecond vehicle body, most preferably a method of making a vehicle cabsuspensions for controlling the motion between a first body cab 22 and asecond body frame 24. The method includes providing the longitudinaldamper tubular housing having a longitudinally extending axis, thelongitudinal damper tubular housing 34 having inner wall 38 forcontaining a magnetorheological fluid within the tubular housing. Theprovided longitudinal damper tubular housing 34 has a first upper end 60and a second distal lower end 58, with the housing centered about axis36. The method includes providing piston rod bearing assembly 54 havingpiston rod bearing seal interface length BL for supporting damper piston42 within the longitudinal damper tubular housing 34. The methodincludes providing cantilevered damper piston 42 including piston head44 and longitudinal piston rod 52. Cantilever piston rod 52 supports thepiston head 44 within the longitudinal damper tubular housing, with theupper piston rod bearing assembly 54 disposed between the longitudinaldamper tubular housing and the longitudinal piston rod. The methodincludes disposing the piston rod bearing assembly 54 in thelongitudinal damper tubular housing 34 proximate the first upper end 60.The method includes receiving the damper piston longitudinal piston rod53 in the piston rod bearing assembly 54, wherein the piston head 44 ismovable within the damper tubular housing along the longitudinal lengthof the tubular housing, with the damper piston head providing a firstupper variable volume magnetorheological fluid chamber 46 and a secondlower variable volume magnetorheological fluid chamber 48, the damperpiston head having a fluid flow gap 50 between the first upper variablevolume magnetorheological fluid chamber and the second lower variablevolume magnetorheological fluid chamber with a piston head fluid flowinterface length HL with contact between the piston head and the dampertubular housing inner wall inhibited. The method includes providingmagnetorheological damper fluid 40 and disposing the magnetorheologicaldamper fluid 40 in the damper tubular housing 34. The damper providesfor controlling the relative motion between the first body 22 and thesecond body 24. Preferably the method includes providing thelongitudinal air strut gas spring 64, and aligning the longitudinalstrut gas spring with the longitudinal damper tubular housinglongitudinally extending axis 36 with the strut air spring andmagnetorheological damper aligned and packaged together with the gasspring encompassing the magnetorheological damper, preferably with theupper end 60 and the piston rod 52 substantially housed within the gasspring 64, preferably with the upper end of strut including the upperstrut end head member 66 for attachment to the uppermost first or secondbody. Preferably the upper strut end head member 66 includes theelectrical power input and the compressed air gas input, along with thestrut control system with electronic control circuit boards 74, gasspring air sleeve leveling valve 76. In preferred embodiments the upperstrut end head member 66 includes the CAN-Bus electrical connection forreceiving outside the strut control signals in addition to electricalpower input into the strut. In preferred embodiments the upper strut endhead member 66 includes the damper sensor system with the end ofmagneto-strictive longitudinal sensor 80 that is aligned and housedwithin the piston rod. Preferably the piston rod bearing assembly 54 isprovided with the piston rod bearing seal interface length BL greaterthan the HL. Preferably the upper volume compensator 62 is provided anddisposed proximate the piston rod bearing assembly 54. Preferably theupper piston rod bearing assembly includes the bearing holder whichreceives the first upper bearing and the distal second lower bearing toprovide the piston rod bearing seal interface length BL. Preferably theupper piston rod bearing assembly includes the bearing holder whichreceives the at least first bearing and includes the compliance membercavity for receiving the volume compensator gas compliance member.Preferably the upper piston rod bearing assembly includes the bearingholder which receives the at least first bearing and has the sensortarget magnet holder which receives the target magnet for themagnetostrictive sensor in the non-magnetic piston rod. Preferably themagnetorheological fluid damper includes the upper volume compensator,with the volume compensator proximate the piston rod bearing. Preferablyat least a first cantilevered magnetorheological fluid damper, and atleast a second cantilevered magnetorheological fluid damper are disposedbetween the first body and the second body. Preferably the at least athird cantilevered magnetorheological fluid damper is disposed betweenthe first body and the second body.

Preferably the invention includes the method of making the controllabledamper for controlling motion. Preferably the method includes providingthe longitudinal damper tubular housing having the longitudinallyextending axis, the longitudinal damper tubular housing having the innerwall for containing the magnetorheological fluid within the tubularhousing, the longitudinal damper tubular housing having the first upperend and the second distal lower end. The method includes providing thepiston rod bearing assembly, the piston rod bearing assembly having thepiston rod bearing seal interface length BL for supporting the damperpiston within the longitudinal damper tubular housing. The methodincludes providing the cantilevered damper piston, the damper pistonincluding the piston head and the longitudinal piston rod for supportingthe piston head within the longitudinal damper tubular housing. Themethod includes disposing the piston rod bearing assembly in thelongitudinal damper tubular housing proximate the first upper end. Themethod includes receiving the damper piston longitudinal piston rod inthe piston rod bearing assembly, wherein the piston head is movablewithin the damper tubular housing along the longitudinal length of thetubular housing, with the damper piston head providing the first uppervariable volume magnetorheological fluid chamber and the second lowervariable volume magnetorheological fluid chamber, the damper piston headhaving the fluid flow gap between the first upper variable volumemagnetorheological fluid chamber and the second lower variable volumemagnetorheological fluid chamber with the piston head fluid flowinterface length HL, with HL<BL and contact between the piston head andthe damper tubular housing inner wall inhibited. Preferably the methodincludes providing the upper volume compensator, and disposing thevolume compensator proximate the piston rod bearing assembly. Preferablythe method includes providing the upper strut end head member with theelectrical power input and disposing the strut end head member proximatethe damper tubular housing first end. Preferably the method includesproviding the upper piston rod bearing assembly with the bearing holdersupport structure which receives the first upper bearing and the distalsecond lower bearing to provide the piston rod bearing seal interfacelength BL. Preferably the method includes providing the upper piston rodbearing assembly with the bearing holder support structure whichreceives at least the first bearing and includes the compliance membercavity for receiving the volume compensator gas compliance member.Preferably the method includes providing the upper piston rod bearingassembly with the bearing holder support structure which receives atleast the first bearing and includes the sensor target magnet holderwhich receives the target magnet. Preferably the method includesproviding the piston head with the injected pressurized polymerovermolded electromagnetic coil.

In an embodiment the invention includes a method of making acontrollable damper for controlling motion. The method includesproviding a longitudinal damper tubular housing 34 having alongitudinally extending axis 36. The provided longitudinal dampertubular housing 34 having an inner wall 38 for containing amagnetorheological fluid 40 within the tubular housing. The longitudinaldamper tubular housing 34 has a first upper end 60 and a second distallower end 58. The method includes providing a piston rod bearingassembly 54, the piston rod bearing assembly having a piston rod bearingseal interface length BL for supporting a damper piston 42 within thelongitudinal damper tubular housing 34. The method includes providing adamper piston 42, the damper piston including a magnetorheological fluidpiston head 44 and a longitudinal piston rod 52 for supporting thepiston head within the longitudinal damper tubular housing 34. Themagnetorheological fluid piston head 44 includes an insulating injectedpressurized polymer overmolded electromagnetic magnetorheological fluidcoil 94. The controllable magnetorheological fluid damper pistoninsulating encapsulant injected pressurized polymer overmoldedelectromagnetic coil 94 and magnetic poles 96 preferably having ODssized to provide the predetermined gap 50 Pgap with the housing innerwall ID, with the gap 50 maintained to inhibit contact with the wall 38and to provide the fluid flow gap 50 with the coil 94 producing amagnetic field for controlling magnetorheological fluid flow through thegap. The controllable piston head electromagnetic coil 94, upper andlower magnetic poles 96 with a variable applied current producing acontrolling magnetic field for controlling the flow ofmagnetorheological fluid 40 between the upper and lower chambers 46 and48, with the electromagnetic coil 94 comprised of the modular componentelectrically insulated injected pressurized polymer overmoldedelectromagnetic magnetorheological fluid coil 94. The preferred modularcomponent injected pressurized polymer overmolded electromagneticmagnetorheological fluid coil 94 is shown in FIG.7A-I. Preferably the EMcoil insulated wire 102 is wound on the non-magnetic plastic polymerbobbin 104, with the coiled wire 102 on the bobbin 104 pressureovermolded with the injected pressurized polymer 110 in the pressurizedinjection overmold 106 under an applied pressure 107. Preferably thenon-magnetic plastic polymer bobbin 104 and the injected pressurizedpolymer 110 are comprised of substantially the same base polymer, in apreferred embodiment the bobbin 104 and the pressurized injectionovermold polymer 110 are comprised of nylon. In a preferred embodimentthe bobbin 104 is comprised of a glass filled nylon and the pressurizedinjection overmold polymer 110 is comprised of a nylon, preferably anon-glass-filled nylon. In a preferred embodiment the bobbin 104 and theovermold polymer 110 are comprised of a common polymer, preferably withthe common polymer comprised of a nylon. Preferably the pressurizedinjection overmolded EM coil 94 includes first and second wire pins 108for connection with a current supply wire circuit 100 that supplies thecontrolling current outputted by the damper control system. Preferablythe modular component pressurized injection overmolded EM coil 94 issandwiched between the upper and lower magnetic metal poles 96, toprovide the current controllable EM coil piston head 44. The modularcomponent pressurized injection overmolded EM coil 94 overmolded EM coiland poles 96 provide a magnetic field for controlling magnetorheologicalfluid flow proximate the piston head EM coil. The method includesdisposing the piston rod bearing assembly 54 in the longitudinal dampertubular housing 34 proximate the first upper end 60. The method includesreceiving the damper piston longitudinal piston rod 52 in the piston rodbearing assembly 54, wherein the magnetorheological fluid piston head 44is movable within the damper tubular housing along the longitudinalstroke length of the tubular housing and the axis 36, with the damperpiston head 44 providing first upper variable volume magnetorheologicalfluid chamber 46, second lower variable volume magnetorheological fluidchamber 48, and the fluid flow gap between the first upper variablevolume magnetorheological fluid chamber and the second lower variablevolume magnetorheological fluid chamber. The method includes providing amagnetorheological damper fluid 40 and disposing the magnetorheologicaldamper fluid 40 in the damper tubular housing 34 wherein a currentsupplied to the injected pressurized polymer overmolded electromagneticmagnetorheological fluid coil 94 controls the flow of themagnetorheological damper fluid 40 proximate the injected pressurizedpolymer overmolded electromagnetic magnetorheological fluid coil 94. Themethod includes injection molding a polymer 110 with a positive pressureinto a overmold 106 containing the wire wrapped electromagnetic coilnonmagnetic plastic bobbin 104 to provide the plastic modular injectedpressurized polymer overmolded electromagnetic magnetorheological fluidcoil 94 for assembly into the piston head 44. Preferably the EM coilinsulated wire 102 is wound on a non-magnetic plastic bobbin 104 withthe coiled wire and bobbin pressure overmolded with an injectedpressurized polymer 110 in a predetermined sized cavity overmold 106under pressure. Preferably the overmolded EM coil 94 includes first andsecond wire pins 108 for connection with a current supply circuit 100.Preferably the modular component EM coil 94 is sized and shaped to besandwiched between upper and lower magnetic metal poles 96. Preferablythe wire 102 is wound on non-magnetic plastic bobbin 104, and thenplaced in coil overmold 106, with insulating injected pressurizedpolymer nylon polymer 110 overmolded around the bobbin and wire.Preferably the piston head 44 and its overmolded EM coil 94 and poles 96are sized to provide predetermined gap 50 with the housing inner wall38, with the EM coil magnetic field controlling fluid flow 40 proximatethe piston head EM coil 94. Preferably the damper overmolded EM coil 94in damper 32 provides for controlling the relative motion between firstbody 22 and the second body 24, preferably with the damper 32 providinga controllable strut 30. Preferably the damper overmolded EM coil 94 isutilized in the making of single ended dampers 32 as compared to doubleended dampers, preferably with the rod 52 terminating with the pistonhead 44 that contains the coil 94. Preferably the piston head 44 is freeof internal fluid flow conduits, preferably substantially all fluid flowis between piston head and housing through the magnetorheological fluidflow gap proximate the EM coil OD, preferably with the piston 42 havinga constant bearing length with the piston head 44 having no bearingcontact with the housing inner wall 38. In alternative preferredembodiments the piston head 44 has a wear band and contact with thehousing wall 38. Preferably the method includes providing upper volumecompensator 62, and disposing the volume compensator 62 proximate thepiston rod bearing assembly 54. Preferably the volume compensator 62 isadjacent the upper piston rod bearing 54, preferably with the bearingholder support structure and volume compensator housing integrated intoan upper bearing gas charged compliance member. Preferably the gascompliance volume compensator 62 is in fluid communication with thefirst upper variable volume magnetorheological fluid chamber 46, withthe volume compensator proximate the upper bearing 56 and the piston rod52, preferably with the upper fluid chamber 46 and volume compensator 62in use oriented on the top end of the damper relative to the force ofgravity. Preferably the damper components provide for dry assembly ofthe damper piston in the housing with magnetorheological fluid 40disposed into the damper after the piston is assembled into the housing,and then gas pressure charging of gas compliance volume compensator 62.Preferably the piston rod bearing assembly bearing holder supportstructure 55 includes fluid flow conduits 92 to allow flow of fluid 40into and out of the volume compensator 62, preferably with the conduitsproviding for greater flow than the magnetorheological piston head gap50. Preferably the method includes providing upper strut end head member66 with an electrical power input 68 and disposing the strut end headmember 66 proximate the damper tubular housing first end 60, with thehead member providing the controlling current to the EM coil 94 throughcircuit 100. Preferably the strut end head member 66 includes thecontrol system 72 with electronic control circuit boards 74, preferablyalso including CAN-Bus electrical connection 78 for receiving outsidethe strut control signals in addition to electrical power input 68.Preferably the head member 66 includes a damper sensor system,preferably with the end of the magneto-strictive longitudinal sensor 80that is aligned and housed within the piston rod 52. Preferably theupper strut end head member housing 66 includes the control system ofthe magnetorheological damper 32 and the gas spring 64 for controllingpneumatic leveling of the strut. Preferably the damper is an intelligentself-contained damper system with the head member 66 containing theelectronics control system that receives sensor inputs and control theelectrical current supplied to the EM coil in the piston head to controlthe damper, preferably with control electronics including accelerometersensors 120, preferably with a 2-axis alignment oriented with the axis36. Preferably the upper strut end head member housing cavity 66 housesthe electronic control sensor system circuit board or boards 74,preferably with the circuit board plane in alignment with the damperlongitudinal axis 36 so the circuit board 74 is substantially verticallyoriented in use with a lower end and an upper end, with the circuitboard having a first accelerometer 120 and a second accelerometer 120normal to the first, preferably with first accelerometer sensing axis122 in alignment with the damper longitudinal axis 36 and the secondaccelerometer sensing axis 122 oriented perpendicular thereto.Preferably the provided upper piston rod bearing assembly 54 includesbearing holder support structure 55 which receives first upper bearing56 and distal second lower bearing 56 to provide the piston rod bearingseal interface length BL. Preferably the upper piston rod bearingassembly 54 includes a bearing holder support structure 55 whichreceives at least a first bearing 56 and includes a compliance membercavity 82 for a volume compensator gas compliance member 84. Preferablythe upper piston rod bearing assembly 54 includes a bearing holdersupport structure 55 which receives at least a first bearing 56 andincludes a sensor target magnet holder 86 which receives a target magnet88 for the magnetostrictive sensor 80 in the non-magnetic piston rod 52.Preferably the damper is dry assembled, then filled withmagnetorheological fluid 40, then closed and sealed, preferably throughthe second lower end 58, preferably with a lower end stopper memberwhich closes off and seal the damper and provides a lower end attachmentmember for attaching to the lower moving body 22, 24. Preferably thepiston rod 52 is hollow with an inner longitudinal chamber whichincludes a longitudinal magnetostrictive sensor 80, preferably with thepiston rod nonmagnetic such that the permanent magnet target 88 producesa magnetic field sensed along the length of the sensor 80 and detectedby the sensor head end preferably in the upper strut end head member 66.Preferably the piston rod inner longitudinal chamber includes thecurrent supply connection circuit 100, preferably insulated wiresproviding connections from the current source in upper strut end headmember down through rod and connected to the overmolded EM coil pins108. Preferably the lower end of the piston rod inner longitudinalchamber is sealed off, preferably with a sealing member 98 between thelower rod end and piston head, preferably integrated with the rod andpiston head attachment joint. Preferably the overmolded EM coil 94includes an inner overmolded core receiving chamber 112, overmolded toreceive a ferromagnetic core member 114, preferably with the magneticmetal core member 114 that is received in the inner overmolded corereceiving chamber including an extending pole member 116 that extendsout of the receiving chamber 112, preferably having an OD substantiallymatching the OD of the overmolded coil and the OD of the piston head,with the extending pole member 116 providing the upper magnetic polemember 96 of the piston head 44. Preferably the OD of the piston headand the overmolded coil are sized to provide the piston gap Pgap betweenthe OD and the damper tubular housing inner wall ID. Preferably theovermolded coil includes the coil guides 95, preferably with the guidesextending longitudinally along the axis 36 such that they extend overthe magnetic pole members 96, with the guides 95 extending radiallyoutward from the OD into the piston gap Pgap towards the damper tubularhousing inner wall ID.

Preferably the received core member 114 includes an inner core centerchamber 118 centered inside the core and extending pole member OD, theinner core center chamber 118 receiving the lower piston rod end andpreferably the overmolded coil wire pin connectors 108, preferably withthe sealing member 98 between the lower rod end and overmolded coil 94,preferably with the inner core center chamber and the lower piston rodend having mating attachment means, preferably such as matching threadsfor attaching the piston rod 52 with the piston head 44. Preferably theovermolded EM coil 94 includes a longitudinal center axis hub member 124with the EM coil wire pins 108 and a radially extending wire coilconnecting arm structure spokes 126 which provides a containmentstructure for the coil connection wire leads leading from thelongitudinal extending wire pins 108 radially outward to the wound coilon the bobbin, and the received core member 114 includes lower end armreceiving radially extending channels 115 for receiving the extendingwire coil connecting arms structure 126 including the overmoldencapsulated radially extending wire leads. Preferably the overmoldedcoil includes the coil guides 95 centered around the axis 36 andextending longitudinally along the axis 36 such that they extendpartially over an adjacent part of the magnetic pole members 96proximate the overmolded coil, with the guides 95 extending radiallyoutward from the OD into the piston gap Pgap towards the damper tubularhousing inner wall ID, with the guide radial height from the OD sized tothe piston gap dimension Pgap.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the invention withoutdeparting from the spirit and scope of the invention. Thus, it isintended that the invention cover the modifications and variations ofthis invention provided they come within the scope of the appendedclaims and their equivalents. It is intended that the scope of differingterms or phrases in the claims may be fulfilled by the same or differentstructure(s) or step(s).

1. A controllable suspension system for controlling the relative motionbetween a first body and a second body, said controllable suspensionsystem comprised of a strut, said strut including a magnetorheologicalfluid damper, said magnetorheological fluid damper including, alongitudinal damper tubular housing having a longitudinally extendingaxis, said longitudinal damper tubular housing having an inner wall forcontaining a magnetorheological fluid within said tubular housing, adamper piston, said damper piston comprised of a piston head movablewithin the damper tubular housing along a longitudinal length of saidtubular housing, with said damper piston head providing a first uppervariable volume magnetorheological fluid chamber and a second lowervariable volume magnetorheological fluid chamber, said damper pistonhead having a fluid flow gap between the first upper variable volumemagnetorheological fluid chamber and the second lower variable volumemagnetorheological fluid chamber with a piston head fluid flow interfacelength HL, said damper piston having a longitudinal piston rod forsupporting said piston head within said longitudinal damper tubularhousing, said piston supported within said longitudinal damper tubularhousing with a piston rod bearing assembly disposed between saidlongitudinal damper tubular housing and said longitudinal piston rod,said piston rod bearing assembly having a piston rod bearing sealinterface length BL, wherein contact between said piston head and saiddamper tubular housing inner wall is inhibited.
 2. A controllablesuspension system as claimed in claim 1 wherein BL>HL.
 3. A controllablesuspension system as claimed in claim 1 wherein said magnetorheologicalfluid damper includes a volume compensator, said volume compensatorproximate said piston rod bearing assembly.
 4. A controllable suspensionsystem as claimed in claim 1 wherein said strut includes a longitudinalgas spring, said longitudinal gas spring aligned with said longitudinaldamper tubular housing longitudinally extending axis.
 5. A controllablesuspension system as claimed in claim 1 wherein said piston rod bearingassembly includes a bearing holder which receives a first upper bearingand a distal second lower bearing to provide said piston rod bearingseal interface length BL.
 6. A controllable suspension system as claimedin claim 1 wherein said piston rod bearing assembly includes a bearingholder which receives at least a first bearing and includes a compliancemember cavity for receiving a volume compensator gas compliance member.7. A controllable suspension system as claimed in claim 1 wherein saidpiston rod bearing assembly includes a bearing holder which receives atleast a first bearing and includes a sensor target magnet holder whichreceives a target magnet.
 8. A controllable suspension system as claimedin claim 1 wherein said magnetorheological fluid damper includes avolume compensator, said volume compensator proximate said piston rodbearing.
 9. A controllable suspension system for controlling therelative motion between the first body and the second body as claimed inclaim 1, said controllable suspension system including a first strut,said first strut including a magnetorheological fluid damper, saidcontrollable suspension system including at least a secondmagnetorheological fluid damper strut between said first body and thesecond body.
 10. A controllable suspension system as claimed in claim 9,including at least a third magnetorheological fluid damper strut betweensaid first body and the second body.
 11. A controllable suspensionsystem as claimed in claim 1 wherein said damper piston head includes apolymer overmolded electromagnetic coil.
 12. A controllable suspensionsystem as claimed in claim 11 wherein said polymer overmoldedelectromagnetic coil includes a plurality of coil guides.
 13. Acontrollable damper for controlling motion, said controllable damperincluding: a longitudinal damper tubular housing having a longitudinallyextending axis, said longitudinal damper tubular housing having an innerwall for containing a fluid within said tubular housing, a damperpiston, said damper piston comprised of a piston head movable within thedamper tubular housing along a longitudinal length of said tubularhousing, with said damper piston head providing a first upper variablevolume fluid chamber and a second lower variable volume fluid chamber,said damper piston head having a fluid flow gap between the first uppervariable volume fluid chamber and the second lower variable volume fluidchamber with a piston head fluid flow interface length HL, said damperpiston having a longitudinal piston rod for supporting said piston headwithin said longitudinal damper tubular housing, said piston supportedwithin said longitudinal damper tubular housing with a piston rodbearing assembly disposed between said longitudinal damper tubularhousing and said longitudinal piston rod, said piston rod bearingassembly having a piston rod bearing seal interface length BL, whereincontact between said piston head and said damper tubular housing innerwall is inhibited.
 14. A controllable damper as claimed in claim 13wherein BL>HL.
 15. A controllable damper as claimed in claim 13 whereinsaid damper includes a volume compensator, said volume compensatorproximate said piston rod bearing assembly.
 16. A controllable damper asclaimed in claim 13 wherein said damper includes an upper strut end headmember with an electrical power input.
 17. A controllable damper asclaimed in claim 13 wherein said damper piston rod bearing assemblyincludes a bearing holder which receives a first upper bearing and adistal second lower bearing to provide said piston rod bearing sealinterface length BL.
 18. A controllable damper as claimed in claim 13wherein said damper piston rod bearing assembly includes a bearingholder which receives at least a first bearing and a compliance membercavity for receiving a volume compensator gas compliance member.
 19. Acontrollable damper as claimed in claim 13 wherein said damper pistonrod bearing assembly includes a bearing holder which receives at least afirst bearing and a sensor target magnet holder which receives a targetmagnet.
 20. A controllable damper as claimed in claim 16 wherein saidlongitudinal piston rod damper piston rod bearing assembly includes abearing holder which receives at least a first bearing and a sensortarget magnet holder which receives a target magnet.
 21. A controllabledamper as claimed in claim 13 wherein said damper piston head includesan injected pressurized polymer overmolded electromagnetic coil.
 22. Acontrollable damper as claimed in claim 21 wherein said polymerovermolded electromagnetic coil includes a plurality of coil guides,said coil guides aligned with said longitudinally extending axis.
 23. Amethod of making a controllable suspension system for controlling therelative motion between a first body and a second body, said methodcomprising: providing a longitudinal damper tubular housing having alongitudinally extending axis, said longitudinal damper tubular housinghaving an inner wall for containing a magnetorheological fluid withinsaid tubular housing, said damper tubular housing inner wall having andamper tubular housing inner wall ID, said longitudinal damper tubularhousing having a first upper end and a second distal lower end,providing a piston rod bearing assembly, said piston rod bearingassembly having a piston rod bearing seal interface length BL forsupporting a damper piston within said longitudinal damper tubularhousing, providing a damper piston, said damper piston including apiston head and a longitudinal piston rod for supporting said pistonhead within said longitudinal damper tubular housing, said piston headhaving a piston head OD, disposing said piston rod bearing assembly insaid longitudinal damper tubular housing proximate said first upper end,receiving said damper piston longitudinal piston rod in said piston rodbearing assembly, wherein said piston head is movable within the dampertubular housing along the longitudinal length of said tubular housing,with said damper piston head providing a first upper variable volumemagnetorheological fluid chamber and a second lower variable volumemagnetorheological fluid chamber, said damper piston head having a fluidflow gap between the first upper variable volume magnetorheologicalfluid chamber and the second lower variable volume magnetorheologicalfluid chamber, and between the piston head OD and the damper tubularhousing inner wall ID, with a piston head fluid flow interface length HLwith contact between said piston head OD and said damper tubular housinginner wall ID inhibited, providing a magnetorheological damper fluid anddisposing said magnetorheological damper fluid in said damper tubularhousing.
 24. A method as claimed in claim 23, said method includingproviding a longitudinal gas spring, and aligning said longitudinal gasspring with said longitudinal damper tubular housing longitudinallyextending axis.
 25. A method as claimed in claim 23, wherein providingsaid piston rod bearing assembly with said piston rod bearing sealinterface length BL includes providing a length BL>HL.
 26. A method asclaimed in claim 23, said method includes providing a volumecompensator, and disposing said volume compensator proximate said pistonrod bearing assembly.
 27. A method as claimed in claim 23, whereinproviding said piston rod bearing assembly includes providing a bearingholder which receives a first upper bearing and a distal second lowerbearing to provide said piston rod bearing seal interface length BL. 28.A method as claimed in claim 23, wherein providing said piston rodbearing assembly includes providing a bearing holder which receives atleast a first bearing and includes a compliance member cavity forreceiving a volume compensator gas compliance member.
 29. A method asclaimed in claim 23, wherein providing said piston rod bearing assemblyincludes providing a bearing holder which receives at least a firstbearing and a sensor target magnet holder which receives a targetmagnet.
 30. A method as claimed in claim 23 wherein saidmagnetorheological fluid damper includes a volume compensator, saidvolume compensator proximate said piston rod bearing.
 31. A method asclaimed in claim 23 including providing a first magnetorheological fluiddamper, and at least a second magnetorheological fluid damper betweensaid first body and the second body.
 32. A method as claimed in claim 31including providing at least a third magnetorheological fluid damperbetween said first body and the second body.
 33. A method as claimed inclaim 23, said method including providing an overmolded piston head EMcoil.
 34. A method as claimed in claim 33, said method includingproviding said piston head with a plurality of longitudinally extendingguides.
 35. A method of making a controllable damper for controllingmotion, said method comprises: providing a longitudinal damper tubularhousing having a longitudinally extending axis, said longitudinal dampertubular housing having an inner wall for containing a fluid within saidtubular housing, said longitudinal damper tubular housing having a firstend and a second distal end, providing a piston rod bearing assembly,said piston rod bearing assembly having a piston rod bearing sealinterface length BL for supporting a damper piston within saidlongitudinal damper tubular housing, providing a damper piston, saiddamper piston including a piston head and a longitudinal piston rod forsupporting said piston head within said longitudinal damper tubularhousing, disposing said piston rod bearing assembly in said longitudinaldamper tubular housing proximate said first end, receiving said damperpiston longitudinal piston rod in said piston rod bearing assembly,wherein said piston head is movable within the damper tubular housingalong the longitudinal length of said tubular housing, with said damperpiston head providing a first upper variable volume fluid chamber and asecond lower variable volume fluid chamber, said damper piston headhaving a fluid flow gap between the first upper variable volume fluidchamber and the second lower variable volume fluid chamber with a pistonhead fluid flow interface length HL, with HL<BL.
 36. A method as claimedin claim 35 said method includes providing a volume compensator, anddisposing said volume compensator proximate said piston rod bearingassembly.
 37. A method as claimed in claim 35 said method includesproviding an upper strut end head member with an electrical power inputand disposing said strut end head member proximate said damper tubularhousing first end.
 38. A method as claimed in claim 35, whereinproviding said piston rod bearing assembly includes providing a bearingholder which receives a first upper bearing and a distal second lowerbearing to provide said piston rod bearing seal interface length BL. 39.A method as claimed in claim 35, wherein providing said piston rodbearing assembly includes providing a bearing holder which receives atleast a first bearing and includes a compliance member cavity forreceiving a volume compensator gas compliance member.
 40. A method asclaimed in claim 35, wherein providing said piston rod bearing assemblyincludes providing a bearing holder which receives at least a firstbearing and includes a sensor target magnet holder which receives atarget magnet.
 41. A method as claimed in claim 35, wherein providingsaid damper piston including said piston head includes providing aninjected pressurized polymer overmolded electromagnetic coil.
 42. Amethod of making a controllable damper for controlling motion, saidmethod comprises: providing a longitudinal damper tubular housing havinga longitudinally extending axis, said longitudinal damper tubularhousing having an inner wall for containing a magnetorheological fluidwithin said tubular housing, said longitudinal damper tubular housinghaving a first upper end and a second distal lower end, providing apiston rod bearing assembly, said piston rod bearing assembly having apiston rod bearing seal interface length BL for supporting a damperpiston within said longitudinal damper tubular housing, providing adamper piston, said damper piston including a magnetorheological fluidpiston head and a longitudinal piston rod for supporting said pistonhead, said magnetorheological fluid piston head including a pressureovermolded electromagnetic magnetorheological fluid coil, disposing saidpiston rod bearing assembly in said longitudinal damper tubular housingproximate said first end, receiving said damper piston longitudinalpiston rod in said piston rod bearing assembly, wherein saidmagnetorheological fluid piston head is movable within the dampertubular housing along the longitudinal length of said tubular housing,with said damper piston head providing a first upper variable volumemagnetorheological fluid chamber and a second lower variable volumemagnetorheological fluid chamber, said damper piston head providing afluid flow gap between the first upper variable volumemagnetorheological fluid chamber and the second lower variable volumemagnetorheological fluid chamber, providing a magnetorheological damperfluid and disposing said magnetorheological damper fluid in said dampertubular housing wherein a current supplied to said pressure overmoldedelectromagnetic magnetorheological fluid coil controls the flow of saidmagnetorheological damper fluid proximate said pressure overmoldedelectromagnetic magnetorheological fluid coil.
 43. A method as claimedin claim 42 said method includes providing a volume compensator, anddisposing said volume compensator proximate said piston rod bearingassembly.
 44. A method as claimed in claim 42 said method includesproviding an upper strut end head member with an electrical power inputand disposing said strut end head member proximate said damper tubularhousing first end.
 45. A method as claimed in claim 42, whereinproviding said piston rod bearing assembly includes providing a bearingholder which receives a first upper bearing and a distal second lowerbearing to provide said piston rod bearing seal interface length BL. 46.A method as claimed in claim 42, wherein providing said piston rodbearing assembly includes providing a bearing holder which receives atleast a first bearing and includes a compliance member cavity forreceiving a volume compensator gas compliance member.
 47. A method asclaimed in claim 42, wherein providing said piston rod bearing assemblyincludes providing a bearing holder which receives at least a firstbearing and includes a sensor target magnet holder which receives atarget magnet.
 47. A method as claimed in claim 42, wherein saidpressure overmolded electromagnetic magnetorheological fluid coilincludes a plurality of guides.
 48. A method of making a controllabledamper for controlling motion, said method comprises: providing alongitudinal damper tubular housing having a longitudinally extendingaxis, said longitudinal damper tubular housing having an inner wall forcontaining a magnetorheological fluid within said tubular housing, saidlongitudinal damper tubular housing having a first upper end and asecond distal lower end, providing a piston rod bearing assembly, saidpiston rod bearing assembly having a piston rod bearing seal interfacefor supporting a damper piston within said longitudinal damper tubularhousing, providing a damper piston, said damper piston including amagnetorheological fluid piston head assembly and a longitudinal pistonrod for supporting said piston head assembly, said magnetorheologicalfluid piston head assembly including a first upper magnetic pole and asecond lower magnetic pole with an overmolded electromagneticmagnetorheological fluid coil between said first upper magnetic pole andsaid second lower magnetic pole, said first upper magnetic polecomprised of a magnetic material, said second lower magnetic polecomprised of a magnetic material, and said overmolded electromagneticmagnetorheological fluid coil comprised of a electrical conductorinsulated wire coil overmolded with a nonmagnetic polymer with saidnonmagnetic polymer including molded polymer coil guides, disposing saidpiston rod bearing assembly in said longitudinal damper tubular housingproximate said first end, receiving said damper piston longitudinalpiston rod in said piston rod bearing assembly, wherein saidmagnetorheological fluid piston head is movable within the dampertubular housing along the longitudinal length of said tubular housing,with said damper piston head providing a first upper variable volumemagnetorheological fluid chamber and a second lower variable volumemagnetorheological fluid chamber, said damper piston head providing afluid flow gap between the first upper variable volumemagnetorheological fluid chamber and the second lower variable volumemagnetorheological fluid chamber, providing a magnetorheological damperfluid and disposing said magnetorheological damper fluid in said dampertubular housing wherein a current supplied to said overmoldedelectromagnetic magnetorheological fluid coil controls the flow of saidmagnetorheological damper fluid proximate said overmoldedelectromagnetic magnetorheological fluid coil.
 49. A method as claimedin claim 48 wherein said electrical conductor insulated wire coil iscoiled on a nonmagnetic plastic bobbin.
 50. A method as claimed in claim48 wherein said molded polymer coil guides are longitudinally extendingcoil guides.
 51. A method as claimed in claim 50 wherein saidlongitudinally extending coil guides are aligned and centered with saidlongitudinally extending axis.
 52. A method as claimed in claim 51wherein said longitudinally extending coil guides extend over said firstupper magnetic pole and said second lower magnetic pole.
 53. Acontrollable damper for controlling motion, said controllable damperincluding: a longitudinal damper tubular housing having a longitudinallyextending axis, said longitudinal damper tubular housing having an innerwall for containing a fluid within said tubular housing, said dampertubular housing inner wall having a damper tubular housing inner wallID, a damper piston, said damper piston comprised of a piston headmovable within the damper tubular housing along a longitudinal length ofsaid tubular housing, said piston head having a piston head OD, withsaid damper piston head providing a first upper variable volume fluidchamber and a second lower variable volume fluid chamber, said damperpiston head having a fluid flow gap between said piston head OD anddamper tubular housing inner wall ID, and between the first uppervariable volume fluid chamber and the second lower variable volume fluidchamber with a piston head fluid flow interface length HL, said damperpiston having a longitudinal piston rod for supporting said piston headwithin said longitudinal damper tubular housing, said piston supportedwithin said longitudinal damper tubular housing with a piston rodbearing assembly disposed between said longitudinal damper tubularhousing and said longitudinal piston rod, said damper including a meansfor inhibiting contact between said piston head OD and said dampertubular housing inner wall ID.